<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            display: flex;
            width: 70%;
            height: 200px;
            background-color: salmon;
            justify-content: center;
            align-items: center;
            /* 水平和垂直居中 */
        }
        span{
            width: 10%;
            height: 100px;
            background-color: red;
        }
    </style>
</head>
<body>
    <div>
        <span></span>
    </div>
</body>
</html>